Does Birth Control Use Up Breast Cancer Risk?

Using hormonal birth control methods - including newer types of birth control pills, as well as intrauterine devices (IUDs) and implants - may slightly increase women's risk of breast cancer, according to a new study from Denmark.

The new study "confirms that the increased breast cancer risk. that was initially reported with the use of older, often higher-dose formulations also applies to contemporary formulations" of birth control, David Hunter, a professor of epidemiology and medicine at Oxford University's Nuffield Department of Population Health in the United Kingdom, wrote in an editorial that accompanied the study.

Overall, the study found that women who used birth control had a 20 percent increase in their relative risk for developing breast cancer.

A hormone specialist at Brigham and Women's Hospital who deals with contraceptive issues says the study shouldn't alarm those taking oral contraceptives.

"The risk increases with increasing duration of use and persists for more than five years, if used for longer than five years", said study author Lina Morch, a senior epidemiologist with the University of Copenhagen in Denmark.

Even newer lower-dose birth control pills raise a woman's risk of breast cancer, although the actual danger is "quite small", researchers reported Wednesday.

Overall, there was one extra case of breast cancer for every 7,600 women using hormonal contraception for a year.

"The increased risk also with newer progestins in hormonal contraceptives has not been shown consistently before, though progestins in postmenopausal therapy has also been found to increase the risk of breast cancer", she added. That's a lot of cancers, given that 140 million use hormonal contraception worldwide - or about 13 percent of women ages 15 to 49. After all, it means that almost a quarter of American women are doing something that might increase their risk of developing breast cancer by a third-in theory. About 40,000 women died of breast cancer in 2017.

"This is an important study because we had no idea how the modern day pills compared to the old-fashioned pills in terms of breast cancer risk, and we didn't know anything about IUDs", Dr. Marisa Weiss, an oncologist who founded the website breastcancer.org and was not involved in the study told The New York Times.

Most breast cancers are fueled by estrogen. In the meantime, women who are using oral contraceptives might want to speak to their doctors about use before age 35 and after age 35. "However, the risk also with newer progestins was more consistent and convincing than expected, in particular the increased risk with hormone IUD (includes only progestin)".

"That is a very small extra risk".

The findings held even after the researchers took into account some factors that can affect the risk of breast cancer, such as becoming pregnant or having a family history of the disease.

Lindegaard speculated that the hormones in birth control may trigger certain cells that are ready to turn into cancer, he said, given that the risk seems to increase after only a few months of use.

Beyond the fact that they provide an effective means of contraception and may benefit women with menstrual cramping or abnormal menstrual bleeding, "the use of oral contraceptives is associated with substantial reductions in the risks of ovarian, endometrial, and colorectal cancers later in life".